this

Here is one example as to why you would want to use it:

'''java

public class SomeClass{

private String variable;

public SomeClass(String variable){ this.variable = variable; }

}

'''

This tells the compiler that you want to store the contents passed in in the instance variable and not trying to make the argument equal itself. There are more examples that could be listed.

Thanks Jeremy

There's often no difference at all, but sometimes you need to use this to tell the difference between a member and local variable. Let's suppose you have a class that doesn't use the m-prefix convention Treehouse courses use (quite common in the wild). The most natural variable names with often conflict. Using this to tell them apart is a common pattern in Java code.

public class GoKart {
   private String color;

   public GoKart(String color) {   // The parameter, which is essentially a local variable,
                                   // overrides the member of the same name.
      this.color = color;  // this. is necessary to specify the member over the local.
   }